1. Field of the Invention
The present invention is generally related to a marine propulsion unit that provides four or more water inlets at the forward portion of its bullet-shaped gearcase and, more particularly, to a marine propulsion unit which additionally provides side water inlets at the sides of its gearcase housing.
2. Description of the Prior Art
Most marine propulsion systems utilize water cooling to control the temperature of an internal combustion engine. Both outboard motors and stern is drive units take water into their cooling systems through water inlets that are located below the water level of a body of water in which the propulsion unit is operated. A water pump is used to draw water through the openings in the housing of the marine propulsion unit and force the water through cooling channels in the internal combustion engine.
U.S. Pat. No. 4,832,635, which issued to McCormick on May 23, 1989, discloses a nose construction for the gearcase of a marine drive. The marine drive unit includes a lower propeller torpedo housing of generally cylindrical configuration having a longitudinal centerline. A propeller shaft is mounted in the housing for rotation on a axis offset from the centerline. The shaft is journalled in a forward bearing assembly which is held in place by a support adjustably mounted to the housing and on the offset axis. A nose is removably secured to the forward housing end by a mounting bolt which extends into the support on the offset axis. A single multi-purpose opening or port in the forward end of the nose communicates to an interior entry passage in the nose. The entry passage, in turn, merges into a pair of passage branches. One branch is disposed on the offset propeller shaft axis and receives the mounting bolt. The other branch is positioned to communicate with the cooling water passages in the lower unit, and which lead to the marine drive engine. A torque retention and sealing member is disposed between the support and the nose. Furthermore, a torque retention and sealing member is disposed between the bulkhead and the inner end of its passage branch.
U.S. Pat. No. 5,791,950, which issued to Weronke et al on Aug. 11, 1998, discloses a twin propeller marine propulsion unit. The improved marine propulsion unit comprises a vertical driveshaft which is journalled in the lower gearcase and drives a pair of bevel gears. A pair of concentric propeller shafts are mounted in the lower torpedo section of the gearcase and each shaft carries a propeller. A slidable clutch is movable between a neutral, a forward, and a reverse position and serves to operably connect the outer propeller shaft with one of the bevel gears when the clutch is moved to the forward drive position. A gear is mounted for sliding movement in unison with the clutch and acts to operably engage the inner propeller shaft with the second bevel gear when the clutch is in the forward drive position so that both propellers are driven in opposite directions to provide forward motion for the water craft. The propulsion system also includes a dual cooling water pick-up system in which sea water is drawn to the water pump both through a series of vertical inlet ports in the gearcase and through a plurality of inlet holes that are located in the forward end of the lower torpedo section. Exhaust gas from the engine is discharged through the rear end of the lower housing section through axial passages in the hub of the forward propeller and then across the outer surface of the rear propeller.
U.S. Pat. No. 3,487,803, which issued to Alexander on Jan. 6, 1970, describes an outboard drive unit for a watercraft. A generally horizontal propeller shaft is rotatably disposed in the lower unit of an outboard drive and projects from the unit to carry a propeller. A generally vertical drive shaft is rotatably disposed in the drive shaft housing of the outboard drive and extends downwardly into the lower unit with the lower end of the drive shaft spaced above the propeller shaft. A plurality of generally vertical driven shafts are disposed in the lower unit and are drivingly connected to the propeller shaft. Reversing gear means connect the drive shaft to the driven shafts and provide for propeller rotation selectively in the forward and reverse directions. The invention further contemplates a transmission arrangement wherein changes in gear ratio can be made to suit the type of operation contemplated for the drive unit. A plurality of water inlets is provided on the nose of a torpedo-shaped portion of the lower unit.
U.S. Pat. No. 5,009,622, which issued to Dudney on Apr. 23, 1991, discloses cooling systems for marine motors. The cooling system has a coolant path which is external to the motor housing of the motor. The external coolant path is connected across the inlet and outlet of the internal coolant path through which coolant is normally conveyed to cool the hot zones of the motor. A closed circuit is thus formed. The external coolant path includes a heat exchanger arranged to place the coolant in heat exchange relationship with water in which the motor runs. It may also include a header tank for pressure control and topping up purposes. The external path can be in kit form for conversion of existing motors. The motor may be an inboard or outboard motor.
U.S. Pat. No. 5,215,487, which issued to Gruber on Jun. 1, 1993, describes a marine propulsion device water inlet screen. The propulsion device comprises a housing including a side wall having therein a water inlet and having an outer surface which extends generally in the fore and aft direction and which includes a ramped portion having a forward end and sloping rearwardly and outwardly from the inlet, and a forwardly-facing portion partially defining the inlet and extending inwardly from the forward end of the ramped portion, a water inlet screen covering the inlet and including a inner surface which slopes rearwardly and outwardly and which engages the ramped surface portion of the housing, screws for securing the screen to the housing, and a propeller shaft rotatably supported by the housing.
U.S. Pat. No. 4,016,825, which issued to Pichl on Apr. 12, 1977, discloses a device for driving a boat propeller and cooling water pump. A device for powering a propeller and a cooling water pump by a boat engine via a downwardly directed drive leg is disclosed, which supports a hollow intermediate shaft for driving the propeller shaft. Between the crankshaft and the intermediate shaft there is arranged a reversible gear device. A shaft for powering the cooling water pump impeller is rigidly attached to the engine crankshaft and rotatably passes through the intermediate shaft of the impeller.
U.S. Pat. No. 3,447,504, which issued to Shimanckas on Jun. 3, 1969, discloses a marine propulsion lower unit. The marine propulsion device comprised a lower unit including therein a rotatably mounted propeller shaft extending only at one end from the lower unit and a second shaft rotatably mounted in the lower unit and extending in acute angular relation to the propeller shaft. A third shaft is rotatably mounted in the lower unit and double gearing connections are provided between the propeller shaft and between the second and third shafts.
U.S. Pat. No. 5,766,046, which issued to Ogino on Jun. 16, 1998, described a cooling water pickup for a marine propulsion unit. The improved water pickup arrangement for a marine propulsion device for picking up cooling water for the propelling, water cooled internal combustion engine, is disclosed. The lower unit has a bullet-shaped portion and the water inlet openings are formed at the forward and upper ends of this portion.
U.S. Pat. No. 5,522,745, which issued to Rodskier on Jun. 4, 1996, describes a boat propulsion unit. The unit is intended to be suspended on the outside of the boat transom and comprises a propeller drive shaft housing, a suspension arrangement intended to be fixedly secured to the transom, and a pivot for the drive shaft housing to allow pivotal displacement of the drive shaft housing relative to the suspension arrangement about a pivot axis in a vertical plane and a pivot axis in a horizontal plane. A steering device effects pivotal displacement of the drive shaft housing about the first mentioned axis, and trim end tilt structure effects pivotal displacement of the drive shaft housing about the second-mentioned axis. The trim structure comprises at least one piston-cylinder arrangement having a cylinder space in communication with a water inlet such that the ram pressure created by the water flowing into the water inlet and dependent on the speed of the boat during forward motion generates a pressure in the cylinder space which strives to trim the propulsion unit away from the transom, and a spring the force of which acts only in the same direction as the water pressure prevailing in the cylinder space. The spring is disposed in the cylinder on only one side of the piston.
U.S. Pat. No. 2,656,812, which issued to Kiekhaefer on Oct. 27, 1953 describes a gearcase unit for outboard motors. The bullet-shaped portion of the gearcase is provided with a plurality of openings formed through a cylindrical portion of the bullet-shaped gear case.
U.S. Pat. No. 5,078,630, which issued to Katsumata on Jan. 7, 1992, discloses an engine cooling system induction arrangement for a marine inboard-outboard and outboard engine. The marine outboard engine has a section of its cooling water suction passage defined by an annular groove formed in the periphery of a bearing housing which accommodates the bearing of the propeller shaft. This allows the suction passage to be connected to a water intake formed on a lower section of the torpedo of the engine without the need to increase the size of the torpedo. This results in a smaller, lighter configuration for the lower case while still allowing the engine to be operated in a super high mount operating mode which is appropriate for use with a super cavitation propeller, due to the low position of the cooling water intake.
U.S. Pat. No. 4,832,639, which issued to Karls et al on May 23, 1989, discloses a marine drive with an air trap for an auxiliary water inlet. The marine propulsion unit has a depending gearcase with one or more water inlet openings in the sides of the gearcase for supplying water to a water pump, and an auxiliary water inlet opening at an anti-ventilation plate above the propeller for supplying additional water to the water pump. The water passage from the auxiliary water inlet opening to the water pump has a portion extending downwardly below the level of the auxiliary water inlet opening and communicating with the side water inlet openings. When the side water inlet openings are below the water line and the auxiliary water inlet is above the water line, water is received in the downwardly extending portion of the second passage and blocks air form flowing from the auxiliary inlet opening to the water pump, to prevent engine overheating.